Fabrication And Modification With Zwitterionic Polymer Of The Oxygen Senitive Nanocapsules

Monitoring of dissolved oxygen（DO）is of great importance in reality practice.There are lots of advantages of optical DO sensor,such as excellent accuracy and precision,full reversibility,non-consumption of oxygen during measurements,enabling online and remotely monitoring and so on,making it one of the most popular methods to detect DO.Oxygen sensing layer（OSL）,as a key component of optical oxygen sensor,is usually prepared by embedding and immobilized the oxygen sensitive probes（OSP）in the matrices via physical method or covalent bonding.However,the OSLs prepared by the physical method are usually prone to leaching of OSP,which make it improper or limited to measure DO in long-term monitoring,microbial environment and living body.In the present work,in order to eliminate the OSP leaching,the OSP were encapsulated in a cross-linked fluorinated polymer nanocapsule（FNC）,in which the fluorinated polymer can promote the diffusion of oxygen molecules in shells efficiently to enhance the performance of the optical oxygen sensor based on FNC.Furthermore,modification of FNC with zwitterion was carried out and a zwitterion nanocapsule（ZNC）with OSP entrapped was synthesized for monitoring DO in microbial environment and living body and its performance of resistance to protein adsorption also was investigated.The details are described as following.FNC and ZNC were synthesized via interfacial confined reversible addition fragmentation chain transfer（RAFT）miniemulsion polymerization with ruthenium（Ⅱ）phenanthroline complex（[Ru（dpp）₃]Cl₂）as the OSP,1H,1H,7H-dodecafluoroheptyl methacrylate（DFMA）and 2-（dimethylamino）ethyl methacrylate（DMAEMA）as the monomers for FNC and ZNC respectively and divinylbenzene（DVB）as the crosslinker.FNC was characterized with TEM、SEM、FTIR、XPS、fluorescent spectra and leaching measurement experiment,and the result shows that FNC has spherical morphology with core-shell structure and OSP was successfully encapsulated and immobilized in FNC in which the fluorescent properties of OSP have no changes.The crosslinked fluorinated polymer shell not only has extremely high gas permeability,but also prevents the fluorescent dyes from leakage in aqueous as well as in various organic solvents,such ethanol,acetone andtetrahydrofuran（THF）.OSL was obtained by spinning coating with the dispersion of FNC.An optical DO sensor based on FNC was fabricated and its oxygen sensing performance was investigated at room temperature.The result shows that the optical sensor has good sensitivity（7.02）,fast response time（13.5s）,full reversibility,and long-term stability in measuring the DO in aqueous.The optical sensor’s work curve is nonlinear and agrees with the modified Stern-Volmer equation by two-site model,and its response values are hardly affected by p H from 2-12.In addition,the antifouling property of ZNC was investigated by adsorption of bovine serum albumin（BSA）.The capacity of adsorbed BSA to ZNC decreased with the increase of the quaternization degree（QD）of PDMAEMA,which resulted in enhancement of ZNC’s antifouling property.When QD is increased to more than 80%,the capacity of adsorbed BSA decreased slowly and kept almost stable.When QD was 80%,the adsorption quantity of BSA was 0.4μg/mg,which reduced by 65% compared to the one having no quaternization.In short,this showed that the high sensitive and fast responsive optical DO sensor based on FNC is able to achieve long-term and online monitoring of DO,and has a good application prospect of monitoring DO in organism or blood detection after modification with a zwitterionic material.